The study covers the 1.76 million driverless miles that Waymo's cars have registered in San Francisco so far, along with about 5.4 million miles registered elsewhere. It compares data about vehicle crashes of all kinds and finds that Waymo vehicles were involved in crashes resulting in injury or property damage far less often than human-driven cars.

The human benchmark- which Waymo is using to refer to human averages for various driving foibles- is 5.55 crashes per million miles. The Waymo robot benchmark is just 0.6 crashes per million miles. The overall figure for crash rates found Waymo's to be 6.7 times lower (0.41 incidents per 1 million miles) than the rate of humans (2.78 per million). This included data from Phoenix, San Francisco, and Los Angeles.

The report's "Conclusions" section is less than definitive in its findings, noting that the data on police-reported incidents across various jurisdictions may not be consistent or "apples-to-apples." "

The benchmark rates varied considerably between locations and within the same location," the report's authors say.

"This raises questions whether the benchmark data sources have comparable reporting thresholds (surveillance bias) or if other factors that were not controlled for in the benchmarks (time of day, mix of driving) is affecting the benchmark rates."

The report is convincingly thorough and academic in its approach, and seems to be great news for the company as it hopes to scale up -- starting with the enormous LA market.

Waymo, like Cruise previously, has sought to convince a sceptical public that driverless vehicles are safer than humans. And this is another step toward doing so -- even if people will be naturally wary of sharing the road with too many robots.